#include<stdio.h>
void interchange(int * u,int * v);
int main(void)
{
    int x = 5 ,y = 10;
    printf("Originally x = %d and y = %d.\n",x,y);
    interchange(&x,&y);
    printf("Now x = %d and y = %d.\n",x,y);
}

void interchange(int * u,int * v)
{
    int temp;
    temp = *u;
    *u = *v;
    *v = temp;
}